I am working on this tool https://misterm.itch.io/mr-tiles-master (for windows) that generates  a sprite sheet starting from  2 colors or 2 images.

The tools is still work in progress..  You can export the spritesheet in png format but I have to finish to save the settings.

I have also started a Map Editor to test your sprite sheet directly..

If you wanna try and give some feedback or new ideas to improved you can write on the comments of the application.

Thanks in advance.